US2381681A - Airplane and control device therefor - Google Patents

Description

4 F. R. MAXWELL AIRPLANE AND CONTROL DEVICE THEREFOR Original Filed Nov. 12, 1940 2 Sheets-Sheet 1 5am? A. {Lia/rival! Arm/M536.

Patented Aug. 7, 1945 ED- 'ES PATENT-time r CONTROL DEVICE THEREFQR Frank R.'Maxwell, Rose Valley,.la. nl ginazl application 1N ovemb'er 12, 219. 10, Serial :No. 365,347.. BDivided and this application March 17,1943, SerialNou479A35 My present invention relates "to airplanes and more panticwlarly has reference to an airplane wing having arnovel slot and'flap .so intercon- -nected that the opening movement of the slot is under rpositive ":COIItPOI :of the pilot at all times. More specifically, the slot is locked in its closed position against aerodynamic'rforces acting on the nose of the win until the pilot moves the flap.

An object of this invention-is to provide a wing having aninterconnected s-lot and flap in which the connecting linkage is So arranged that it exerts its greatest mechanical force when the greatest aerodynamic "foncesare aotingon the slot or flap.

To :achieve the foregoing and other "objects, this 'invention comprises providing a .slot adjacent to the leading edge of the wing and a flap near the trailing edge of the wing. .The upper and lower openings of the slot :are adapted to he closed lav-covers which conform to the contour of the upper and lower surfaces of the wing in their closed position. Linkage connects the flap to the upper cover and there is aconnection to the lower cover which is operated by movement of the linkage. .A control extendsfrom the op erating linkage to the cock-pit or the fuselage of the airplane :so that the pilot may actuate the slot and :flapby a single control.

The linkage is of such nature that the flap may move through a small angle before the slot opens and the aerodynamic forces working on the leading edge of the "wing cannot open the upper cover until the pilot has moved the flap. Furthem-lore, the'connection to the lower cover will permit the tower cover to-rrnove into contact with the upper cover to give an vairtoil section to the upper cover upon the initial movement of the upper cover and will maintain this air toil section for all .further movement of the nppernover,

thus permittin maximum airflow through the slot.

In the drawings: y v

Figure 1 is a transverse sectional view of an ainplane wing equipped with rmy'novel noseslot and flap combination showing these parts in the.

closed position.

Figure 2 .is a transverse sectional view of an airplane wing equipped with another form of my invention.

Figure 3 .is a transverse sectional View of a stil'l of my novel nose slot and :flapcominternal spars '2, a slot 3 which extends through the wing adjacent to the leading ledge thereof and a. flap *4 provided near the trailing edge of the Wing. The wing 1 is formed with-a recess or well .5 in'which the .flap 4 is pivoted as shown :at -6.. -An :arm 1 is attached to the flap and an operating iI'Od, 8 is pivoted to the tree end of the arm: .1 as indicated at .9. il he .rod :8 .iswsuitahly connected 'to the .fiap "operating mechanism .(not illustrated) located within thecockpit or fuselage of theaiifplane. n i

There is also attached to the flap l a short :arm 10 to which ispivoteii at :H along [operating slink or push rod t2; As iclearlyzshownci-n :Figure l,

the "operating rod .112 [extends to a {P611113 adjacent to (the slot '3 and is pivoted at [13 to one arm of a hell crank :M which is aivoted 2817 L5 to the ternail structure of the "wing.

'Tlieilupper opening rof the slot 3 isada-pted to :be' closed :by a cover It which is hinged to the nose of the wing :i as shown .at H. A second slot covert-t8 zfor the Jewel, opening of the .slot

.is also hinged at the point I]. As clearly shown in the drawings, when thecovers I 6 and 4:8 are in their closed positions, :they contormto the contounof the upper and lower suntaces-of the wing 1.; therebyafiording :an air-foil section.

A pnshrod il'9 is pivoted to the other arm of therbell-cran k 44, as shown at #20. Thetreeend or the mod it is pivoted tot-he undersur-face of the cover t6, shown at 21. A toggle Jink;22 is hinged to :the :lower cover hit, as shown at 2'2, and an elongatedleverwpis pivoted to the link 22. TIE-he lower 23 is pivoted to the cover It, as shown at 24. and is formed with a short offset portion 25. A red 26 .is pivoted to theroffset portion 25, as'shown at 22!, and the rod '26 is further formed with a lost motion slot 28 in which is adapted to move a pin 2-9 carried by the bell crank 14. The rod 25 :is attached'to one of the internalispars by tension spring 3i]. I

It is thought apparent that :sincethe pivot points 5 'i' ll and t5 are in line when the slot 3 and flap 4 are in theirclosed positions, it is not possible for the aerodynamic forces working on the leadin-g edge of the wing to rock the bell crank M about itsq-pi-vot l5 to oazuse-the upper slot cover it to open. This is :a very important feature :of the present invention in that .it will positively prevent the slot in the leading edge of the wing [firom being .opened except such opening is desired the pilot of l the airplane.

When the pilot operates his control to lower the flap it will be appreciated that thefiap d-may move through :an angle of approximately-ly'ibetore-the bell crank 7M begins to rock about its pivot l5 to open the cover Hi. This is very desirable in that there are certain flight conditions where it is desired to have some flap movement without opening the slot. When the bell crank has rocked suificiently to cause the push rod I9 to open the cover [6 slightly, the offset portion 25 and the lever 23 and link 22 will move the lower slot cover I8 into a well or recess 3| provided in the upper slot cover I6. This will give an airfoil section to the upper cover I6 and as the upper slot cover is moved further, the lower slot cover will remain in its nested position and thus afford optimum airflow through the slot 3.

In Figure 2, there is covered a still further form of my invention. In this modification, the operating link I2 is hinged at 50 to one arm of a bell crank 51 and the bell crank is pivoted at 52 to the internal structure of the wing I. A second operating link 53 is pivoted to the other arm of the bell crank, as shown at 54. The opposite end of the link 53 is pivoted at l3 to the bell crank I4 which operates the upper slot cover I6.

It should be noted that when the slot 3 and the flap 4 are in the closed positions the pivot points I3, 54 and 52 are in a straight line, thereby affording a lock, and it is not possible for the aerodynamic forces acting on the nose of the wing I to open the upper slot cover I6. Clearly, the slot 3 can only be opened when the pilot manipulates his controls to lower the flap 4 to rock the bell crank about the pivot 52.

In Figure 3 there is shown another form of slot and flap combination in which the mechanism holding the upper slot cover I6 in its closed positiOn is adjacent to the slot 3. In this form, it can be seen that the operating link [2 is pivoted at l3 to a lever 60 which is pivoted at '6I to the internal structure of the wing I at a point adjacent to the nose. A push rod 62 is pivoted to the lever 60 as shown at 63, and to the upper slot cover as shown at 64. The rod 62 is curved as indicated at 65 so that it will not interfere with the pivot point 6| of the lever 60.

Pivoted to the lower slot cover I8 as shown at 66 is a short rod 6'1. Secured to the end of the rod 61 is a sleeve 68 in which is disposed a helical spring 69. Pivoted at to the lever 60 is a rod II which extends into the sleeve 68. A pin '12 provided on the rod 'II projects through a lost motion slot 13 provided in the sleeve 68. It is thought obvious therefore that when the lever 60 is moved about its pivot 6| by the lowering of the flap 4, the rod II will slide in the sleeve 68,1compressing the spring, thereby causing the lower slot cover [8 to move to the broken line position shown in Figure 1 whereby a smooth contour is provided in the slot 3.

It should be further observed that the pivot points l3, SI and 63 are in a substantially straight line when the slot 3 and the flap 4 are in their closed positions. As a result, it is not possible for the upper slot cover l6 to be opened by virtue of the forces acting on the wing I.

By placing the straight line pivot points l3,

6|, 63 adjacent the slot cover I6, the relatively great aerodynamic forces tending to open the slot will be confined to this structure and not be transmitted to the other control mechanism and surfaces.

In Figures 4, 5 and 6, I have shOWIl diagrammatically the linkage that interconnects the slot and flap which tend to normally balance each other aerodynamically.

It will be noted that when the flap approaches its position normal to the airstream, th air forces affecting the flap movement decrease toward zero. Simultaneously, the slot is closing and the air forces tending to open the slot cover increase. During this movement, the toggle effect of the linkage is also increasing which compensates for the increased air force on the slot cover.

From the foregoing description, it will be appreciated that I have provided a wing having an interconnected slot and flap in which the connecting linkage is so arranged that it exerts its greatest mechanical force when the greatest aerodynamic forces' are acting on the slot or flap.

More specifically, as the flap and slot move, the toggle effect of the linkage tends to balance the aerodynamic forces acting on them.

While I have shown and described the preferred embodiment of my invention, I wish it to be understood that I do not confine myself to the precise details of construction herein set forth by way of illustration, as it is apparent that many changes and variations may be made therein, by those skilled in the art, without departin from the spirit of the invention, or exceeding the scope of the appended claims.

This application is a division of application filed by me November 12, 1940, Serial No. 365,347, now Patent No. 2,321,337, granted June 15, 1943.

What I claim and desire to protect by Letters Patent is:

1. An airfoil comprising a main section and a slot cover supported adjacent the leading edge of the 'main section and adapted to be opened to form a slot, a rear flap supported from the main section and members forming interconnected operative connections between said cover and flap whereby they may be rendered cooperatively operative, said operative connections being so arranged that said members will assume relative positions such that independent of increase in the angle of attack of the airfoil in flight as the slot cover opens the force transmitted to the flap through the operative connections increases from about zero in the closed position of the cover to a maximum in its fully opened position to substantially balance the increased force exerted by the flap as it moves to operative positions.

2. An airfoil according to claim 1, characterized by the fact that the interconnected operative connections between the slot cover and the flap include a toggle so arranged that as the slot cover opens and the flap is rendered operative in flight the members forming the toggle will change angularity with relation to the force acting on the slot cover to increase the force transmitted to the flap to substantially balance the force exerted by the flap.

3. An airfoil according to claim 1, characterized by the fact that the interconnected operative connections between the slot and the flap are so arranged that on operation thereof in flight the flap will be rendered substantially effective before the slot cover opens sufficiently to render the slot consequentially effective.

4. An airfoil according to claim 1, characterized by the fact that the interconnected operative connections between the slot and the fiap are so arranged as to be in at least a dead center position with respect to opening movement of the cover and to move out of'dead center position to open the cover.

FRANK R. MAXWELL.

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